//方法一
char * my_strcpy(char *dest, char *src)
{
    char *ret = dest;
    while(*dest ++ = *src ++)
    {
        ;
    }
    return ret;
}
//方法二
void my_strcpy(char des[], char src[])
{
    int i = 0;
    while(src[i])
    {
        des[i] = src[i];
        i ++;
    }
    des[i] = '\0';
}